DocuSign has also confirmed that Mary Meeker, the Kleiner Perkins Caufield & Byers partner (and former Morgan Stanley analyst) who’s most famous for her reports on the mobile industry, is joining the DocuSign board. It looks likely that Kleiner led the new round, but neither DocuSign nor Kleiner has confirmed that. (For now, the company will only say that the funding comes from “premier investors, public funds, and strategic tech-industry leaders.”)

Founded in 2004, DocuSign describes itself as “the industry standard in electronic signature” — and that’s probably a fair description. The company says 18 million people have used its products to sign 120 million documents, and that more than 150,000 documents are “DocuSigned” every day.

DocuSign previously raised a total of $56.4 million from Frazier Technology Ventures, Ignition Partners, Sigma Partners, Scale Venture Partners, Salesforce.com, and others, with its Series C announced in December 2010.

I’ll be speaking to CEO Keith Krach later today and will update this post with his comments.

DocuSign will use the new funding to invest in three main areas, Krach says — research and development, expanding into new industries, and expanding internationally.

Apparently Krach and Meeker have known each other since Ariba (where he was CEO) went public more than a decade ago, when she was at Morgan Stanley. Asked whether Meeker is approaching this as a mobile investment primarily, Krach says the company’s mobile apps are “absolutely taking off.” At the same time, he says Meeker’s also just looking for disruptive technologies.

“By the second half of this decade, the vast majority of signatures are going to be electronic,” Krach says. “Every person is a potential customer.”

(Also, an earlier version of the story said the amount raised was $50 million, because that’s what DocuSign said initially, but the press release says $47.5 million, which was also the amount included in the SEC filing.)

BioMary Meeker joined Kleiner Perkins Caufield & Byers in December 2010. She focuses on investments in the firm’s digital practice and helps lead KPCB’s Digital Growth Funds, targeting high-growth Internet companies that have achieved rapid adoption and scale. Mary serves on the boards of Square, Lending Club and DocuSign and has been involved in KPCB’s investments in SoundCloud, LegalZoom, Spotify, …